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Growth Curves

 
1.3 Growth Curves
 
Types of Plants Based on Life Cycles
Annual Plants
  • Annual plants are plants that have only one life cycle for a season or a year.
  • These plants usually die after produce flowers and fruits.
  • Examples of annual plants is as shown below:

The image is a diagram showing examples of annual plants. In the center, there is a blue circle labeled ‘Examples of Annual Plants.’ Four orange circles surround the central circle, each connected by dashed arrows. The orange circles are labeled ‘Corn,’ ‘Tomato,’ ‘Mustard,’ and ‘Onion.’ The logo ‘Pandai’ is at the bottom of the central circle.
Biennial Plants
  • Biennial plants are plants that ended their life cycle in two years by two growing systems.
  • First year is the phase of vegetative, which is the growth of leaves and stems structures.
  • At the second year, the plants produce flowers and fruit.
  • Examples of biennial plants is:
    • Tulip plants.
    • Spinash.
    • Cabbages.
Perennial Plants
  • Perennial plants are the plants which can live longer although after the formation of flowers and fruits.
  • All the perennial plants are woody plants.
  • These plants can continue to live as long as do not infected by diseases or destroyed by humans,animals or disasters.
  • Examples of perennial plants is as shown below: 

The image is an infographic titled ‘Examples of Perennial Plants.’ It features a central blue circle with the title, connected by dashed arrows to four orange circles. Each orange circle lists a different perennial plant: ‘Durian,’ ‘Mango,’ ‘Chillies,’ and ‘Papaya.’ At the bottom center, there is a logo that says ‘Pandai.’
 
Growth Curve in Plants
The Growth Curve of Annual Plants

This graph shows the dry mass (in grams) of a subject over a period of 25 weeks. The x-axis represents time in weeks, while the y-axis represents dry mass in grams. The curve starts at point A (0 weeks, 5 grams), rises steadily to point B (10 weeks, 20 grams), continues to increase to point C (20 weeks, 50 grams), and then slightly decreases towards point D (25 weeks, 45 grams). The background of the graph is shaded from light yellow at the top to white at the bottom.

  • The growth curve is a sigmoid curve.
  • Stage A: Decreasing dry mass:
    • Food stored in the cotyledon is used for germination before the leaves emerge to carry out photosynthesis. 
  • Stage B: Increasing dry mass:
    • The rate of growth increases rapidly.
    • This is because the plant has carried out photosynthesis.
  • Stage C: Constant dry mass:
    • The rate of growth is zero.
    • Plant is matured at this stage.
  • Stage D: Decreasing dry mass:
    • Happens slowly because of aging, lower rate of photosynthesis, shedding of leaves and flowers and seed dispersal.
The Growth Curve of Biennial Plants

The graph shows the dry mass (g) of an organism over 50 weeks. The x-axis represents time in weeks, while the y-axis represents dry mass in grams. The curve starts at 0.4 g, increases steadily to around 1.6 g by week 20, dips slightly, and then rises again, peaking at approximately 2.4 g by week 45 before slightly declining.

  • The growth curve has two sigmoid curves which are combined.
  • First growth season:
    • Plants produce leaves, photosynthesis takes place.
    • Food is stored in tubers.
  • Second growth season:
    • The food stored is used to produce flowers and seeds.
The Growth Curve of Perennial Plants

The graph shows the growth of a plant over a period of 10 years. The x-axis represents time in years, ranging from 0 to 10, while the y-axis represents height in meters, ranging from 0 to 5. The data points are marked with blue dots, and a red line indicates the average growth trend. The background of the graph is shaded in yellow.

  • The growth curve is a series of small sigmoid curves.
  • Every year the growth curve is a sigmoid curve. Growth occurs throughout the lifespan of the plant.
  • The rate of growth is high during spring and summer. High light intensity increases the rate of photosynthesis.
  • The rate of growth decreases in winter.
 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.
Chapter : Plant Tissue Organisation and Growth
Topic : Growth Curve
Form 5 Biology
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